A belt press normally has a plurality of upper and a plurality of lower traverses respectively having lower and upper traverse faces with the traverses all parallel and each upper traverse lying above a respective lower traverse. Upper and lower heatable press platens are carried between these traverses and in turn have respective upper and lower platen faces respectively confronting the lower and upper traverse faces. Mechanically or hydraulically actuated means is engaged between each lower traverse and the respective upper traverse for displacing the traverses toward each other and thereby pressing the platens against a belt between them. During a pressing operation the platens bend somewhat from their normally planar shape, as the platens are not made stiff enough to avoid such bending in order to cut down on equipment weight.
Normally the actuating means is provided between only one of the platens and the respective traverses. Such means normally comprises an array of screw-type or hydraulic jacks engaged between this movable platen and the respective traverses, with several such jacks between each traverse and the respective movable platen.
In order to accommodate such jacks, in particular hydraulic ones, it is necessary to cut holes in the traverses. Thus these traverses, which are usually designed to be as light as possible, are rendered rather weak and bendable.
Another disadvantage of this type of system is that even when enormous pains are taken the movable platen is unevenly pressed away from its traverse. The number of jacks must of course be finite so that it is normally not possible to evenly load the movable press platen.